1. Technical Field
The present invention relates to a physical quantity sensor, an electronic device, and a mobile body.
2. Related Art
In recent years, a sensor has been developed that is manufactured using a silicon micro electro mechanical systems (MEMS) technique. As such a sensor, an electrostatic capacitive-type physical quantity sensor is known which has a fixed electrode that is disposed to be fixed and a movable electrode which faces the fixed electrode with an interval therebetween and is provided to be displaceable, and detects a physical quantity such as acceleration and angular velocity based on electrostatic capacity between the two electrodes (for example, refer to JP-A-2010-071911 and JP-A-10-111312).
For example, the physical quantity sensor in JP-A-2010-071911 has two fixed electrode sections and a movable electrode section which are formed separated from one silicon wafer. In the physical quantity sensor, each fixed electrode section has a support conducting section which is fixed to a substrate front surface, an electrode support section with a fixed width dimension which extends linearly from the support conducting section, and a plurality of opposing electrodes which are arranged to form a comb-tooth shape extending from the electrode support section. Meanwhile, the movable electrode section has two support conducting portions which are fixed to the substrate front surface, and support arm portions which extend from respective support conducting portions, a weight section which is disposed in a region interposed by two support arm sections, an elastic support section which supports the weight section with respect to each support arm section, and a plurality of movable opposing electrodes which are disposed extending from the weight section so as to face the plurality of opposing electrodes of the fixed electrode section described above.
In addition, for example, the physical quantity sensor according to JP-A-10-111312 has two mounting bars which are fixed to two anchor joining regions on the front surface of the substrate, two deflection springs which are fixed to each of the both mounting bars, one center bar which is joined to other end sections of four deflection springs, a plurality of movable electrodes which are mounted on the center bar, and a plurality of fixed electrodes which are respectively disposed facing the plurality of movable electrodes being fixed to a plurality of anchor regions on the front surface of the substrate.
In such a physical quantity sensor in the related art, the movable electrode and the fixed electrode are fixed and connected to a substrate via a plurality of connecting sections (support conducting section in JP-A-2010-071911 and anchor joining region in JP-A-10-111312), but a portion of the movable electrode (weight section in JP-A-2010-071911 and center bar in JP-A-10-111312) is positioned in planar view between two connecting sections out of the plurality of connecting sections. For this reason, in the physical quantity sensor in the related art, it is difficult to shorten a distance between the two connecting sections and when the substrate is warped accompanying temperature variance, the warping of the substrate is likely to influence the fixed electrode and the movable electrode via the connecting section to be deformed, and as a result, there is a problem in that temperature characteristics deteriorate. Here, for example, the warping of the substrate accompanying temperature variance occurs due to a linear expansion coefficient difference between the substrate and a member which is joined to the substrate (for example, a structure that includes the movable electrode and the fixed electrode, or a lid member for configuring a package which accommodates the substrate and the structure).